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View Full Version : Fouling membranes WAY too quickly


firebirdude
11/17/2015, 02:41 PM
I have the Spectrapure 90gpd RODI that I've added on two more stages. Ever since I moved to Oklahoma, I've been eating through membranes like you wouldn't believe. Input TDS is about 320-340. I currently use 1 micron sediment depth filter, 1 micron BRS carbon block, 1 micro BRS carbon block, Dow membrane, mixed bed DI resin, mixed bed DI resin. Water temp is ~70F and pressure has always stayed at 80psi at the membrane. I have a flush kit which I turn on for about a minute before and after I make DI water.

With all new filters, everything is golden and I get 90+gpd of output. But after producing maybe ~120 gallons of output, my output flow dwindles down to ~20gpd. I still show 80psi at the membrane and replacing all the filters in the system doesn't change anything, until I replace the membrane. Bam. Back up to 90+gpd output. I have these (http://www.bulkreefsupply.com/insta-test-free-total-chlorine-strips-lamotte.html) test strips and have tested around the 1st of November and again yesterday. 0 free and total chlorine both days. I suppose it's possible the city only uses chlorine occasionally and I just haven't caught one of those days with my test strips yet. Or not. No idea.

Help! What tests can I do? Can I mail in a sample of my water so someone can help me? Or would that not really help much as the city may fluctuate what they put in the water at certain times?

SpectraPure
11/18/2015, 12:32 PM
You need to measure your waste to product ratio. If you aren't wasting enough water your membrane will scale and clog production.

Jeremy

firebirdude
11/29/2015, 06:13 PM
Thank you for your response. Sorry for my slow response.

Just clocked my ratio at 4.6:1. Water is pretty cold today though. Probably 60F. While that will affect output, it shouldn't affect the ratio, no?

SpectraPure
11/30/2015, 09:01 AM
What is the TDS of the tap water, and what is the tds coming out of the RO before the DI?

Jeremy

firebirdude
11/30/2015, 12:01 PM
Tap is 305. Membrane output is ~4.

SpectraPure
11/30/2015, 01:49 PM
Water temperature does change the ratio. I have a flow restrictor dedicated to the summer, and one for the winter.

Jeremy

firebirdude
11/30/2015, 05:07 PM
Fair idea. But I don't think that's my issue. And with new filters/membrane being put in this thing every other time I turn around, I don't think it's anything to do with my setup design, water pressure, waste ratio, or water temp. Gotta be something in the water getting past the sediment and two carbon blocks.

SpectraPure
11/30/2015, 08:22 PM
Well if you have high amount of Chloramines it could be eaten up by ammonia. If you have a high amount of Co2 that could also chew up the DI. Do you make large batches, and turn the system off, or do you leave it on to be automated? What is the ml/min of the product water versus the waste water?

We can figure this out, but the more answers I know the easier it will be to figure out.

=)

Filters are buy one get one half off all week for Cyber Monday week!

Jeremy

firebirdude
11/30/2015, 08:30 PM
One of my two carbon blocks is a "chloramine specific" carbon block. How it's actually different, I have no idea.

I turn on the water, flush for about 60 seconds, turn the flush valve to off, make about 10-15 gallons of output, flush for another 60 seconds, then turn the source water off. I do this about three times a month, between water changes and ATO refilling. After ~5 months I realize that it's taking much longer to fill the bucket than it used to.... then I get ****ed off, post on the forums, reluctantly swap out the membrane and I'm instantly back to great output.

As for ml/min, I have no clue. I had a large graduated pitcher and a stopwatch that I used to measure the 4.6:1 ratio I posted above. I calculated 6.72oz/min of output to 32.22oz/min of waste water. So I guess that would be 198.7341ml/min of product to 952.85912ml/min of waste. :) That's just barely over 75 gallons a day of output. I'm normally closer to 90, but this membrane has had ~30 gallons of output from it (which means it has probably started fouling already LOL) and the water was pretty cold for this test.

Thanks for the Cyber MOnday tip

SpectraPure
12/01/2015, 08:58 AM
In the winter I would expect lower gpd. Water molecules in colder weather are slower. This is pretty normal. It seems like everything is running within spec. Before you replace the membrane again remove all of your filters from the canister to see if your output goes back up. If the pre-filtration clogs up quickly it will have an effect on your production.

Jeremy

firebirdude
12/01/2015, 06:23 PM
Yes, they are in spec at this time. But I just replaced the membrane and have been down this road several times. This newly installed membrane will foul very soon. By the end of the season.

SpectraPure
12/01/2015, 11:46 PM
get a hold of your total water quality report from your municipal water source and email to me at [email protected]

Jeremy

firebirdude
12/19/2015, 09:08 AM
get a hold of your total water quality report from your municipal water source and email to me at [email protected]

JeremyHey Jeremy. I emailed you guys my 2013 and 2014 reports on the 7th. Any feedback?

Thanks for your help!

SpectraPure
12/21/2015, 09:05 AM
I don't remember seeing it. Can you resend?

Jeremy

firebirdude
12/21/2015, 06:45 PM
I don't remember seeing it. Can you resend?

JeremySent to [email protected] .

Or do you have a direct email I can send it to?

SpectraPure
12/22/2015, 09:09 AM
I received it. I sent a message back.

Jeremy